J,H,K PHOTOMETRY IN GLOBULAR CLUSTER OMEGA CENTAURI AND SPREAD OF GIANT BRANCH

J, H, K observations are presented and discussed for a number of the brighter stars in ω Cen. The large spread of the giant branch in the V, (B-V) diagram, which is greatly reduced in an R, (R-I) plot, reappears again in a K, (J-K) plot. At a given R and (R-I), the giants with redder (B-V)'s are fainter in the blue and brighter in the infrared. Some of these stars with redder (B-V)'s suffer excess molecular blanketing in the blue spectral region according to Bessell & Norris. Our results suggest that this excess absorption may be compensated by an excess emission in the infrared. Other stars discussed are red variables, stars on Lloyd Evans' anomalous red giant branch, CH stars and Fehrenbach's star. © 1977 Royal Astronomical Society.